Various types of sensor systems can be employed to detect radiation, such as infrared radiation, emitted by objects within a field-of-view. The radiation emissions from those objects are then analyzed in order to obtain information regarding the characteristics and movement of those objects.
Specifically, radiation from a portion of the field-of-view is scanned across an array of detector elements, and the output signals of the detector elements are sampled and processed. The rate at which the full field-of-view can be processed is called frame rate. Spatial sample rate is scanning type sensor systems can be controlled by the detector signal sample rate and sensor scan rate. In order to provide a rapid coverage of a desired field-of-view, it is necessary to scan the image across the detector element array at a very high speed. However, this reduces the dwell time of the image upon each individual detector element, thereby reducing the amount of energy that can be integrated by each detector element to provide and output signal detectable above the noise level. Moreover, a relatively high sampling rate is required in order to obtain the desired temporal resolution.
A reduction in sampling rate can be provided by slowing the scan rate of the sensor system. However, sensor systems are typically employed where it is desired to monitor a field-of-view, detect a target, and return to the same position in the field-of-view to determine if the target has moved. It is also desirable to provide a high frame rate, that is, to rapidly return to an original field-of-view portion in order to detect variations, or modulations, in intensity of radiation emitted by the target, in order to obtain valuable information concerning the characteristics of the target. If the scan rate of scanning type sensors is slowed down to permit longer integration times and slower sampling rates, the frame rate of the system will be reduced, resulting in a corresponding reduction in the ability to frame-to-frame associate closely spaced objects and measure modulation of targets by comparing target characteristics on successive frames.
The present disclosure provides a method and apparatus for improving frame rate in scanning type sensor systems.